1. Field of the Invention
The present invention relates to a work holding mechanism suitable for material handling/transporting equipment configured to transport a work such as a wafer while holding the work horizontally.
2. Description of the Related Art
A conventional work holding mechanism is disclosed in JP-A-2006-150538, for example. The work holding mechanism described in this document includes a pair of tip pawls provided at a tip of a base member (transport hand), and a pair of clamp pawls for pushing a wafer, which is placed on the base member, toward the tip of the base member. The clamp pawls are pivotable in predetermined directions by an actuating mechanism such as an air cylinder, coil springs, and so on. According to such a holding mechanism, the wafer on the base member can be pushed by the clamp pawls toward the tip of the base member, thereby positioning and holding the wafer on the base member, between the clamp pawls and the tip pawls, preventing the wafer from shifting sideways while it is transported.
However, the conventional work holding mechanism uses an air cylinder to move the clamp pawls, so there is a problem that the material handling/transport equipment cannot be used under vacuum environment.
Further, the actuator for moving the clamp pawls employs a large number of different parts, resulting in a complex mechanical structure and a difficulty in weight reduction and simplification as an entire work holding mechanism.